This invention relates generally to manually operated pump dispensers having particular utility for viscous products such as tooth paste and similar pasty substances.
More specifically, the viscous product dispenser of the invention is of the two-chamber variety having a stationary product discharge spout, one of the chambers being a pump chamber having internal inlet and outlet check valves. And, the dispenser may have a spout cover capable of being swung open at the commencement of pumping and returned to a closed position at the termination of pumping.
U.S. Pat. Nos. 4,301,948 and 4,651,904 each disclose a two-chamber viscous product dispenser having a stationary discharge spout and internal valving for the pump chamber.
It is desired to improve upon such internal valving to simplify the valving structure and arrangement within the dispenser to more efficiently and economically valve the viscous product out of the pump chamber during pumping.
U.S. Pat. Nos. 4,684,044 and 4,691,847 each disclose a viscous product pump dispenser having a discharge spout which reciprocates during pumping, and having a spout cover which functions as an outlet valve during pumping.
It is desireable to improve upon this type of viscous product dispenser by the provision of a spout cover which need not function as an outlet valve for a stationary spout which is opened and closed upon operation of the pump actuator.